Transmitter, receiver and controlling method thereof

ABSTRACT

A transmitter includes: a frame generator configured to generate a frame including a frame starting symbol, at least one data symbol and a frame closing symbol; a pilot and reserved tone inserter configured to insert pilots and reserved tones in at least one of the frame starting symbol, the data symbol and the frame closing symbol such that positions of the reserved tones do not overlap positions of the pilots in the at least one of the frame starting symbol, the data symbol and the frame closing symbol; and a transmitter configured to transmit the frame in which the pilots and the reserved tones are inserted, wherein the reserved tones are not used to transmit data in the frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 17/144,646 filedJan. 8, 2021, is a continuation of U.S. application Ser. No. 16/569,918filed Sep. 13, 2019, which is a continuation of U.S. application Ser.No. 16/025,757 filed Jul. 2, 2018, which is a continuation of U.S.application Ser. No. 15/402,810 filed Jan. 10, 2017, which is acontinuation of U.S. application Ser. No. 14/450,480 filed Aug. 4, 2014,which claims priority from U.S. Provisional Application No. 61/862,158filed on Aug. 5, 2013, U.S. Provisional Application No. 61/876,307 filedon Sep. 11, 2013, and U.S. Provisional Application No. 61/923,804 filedon Jan. 6, 2014 in the United States and Patent and Trademark Office,and Korean Patent Application No. 10-2014-0004024 filed on Jan. 13, 2014in the Korean Intellectual Property Office, the disclosures of which areincorporated herein by reference in their entirety.

BACKGROUND 1. Field

Apparatuses and methods consistent with what is disclosed herein relateto a transmitter, a receiver, and a controlling method thereof, and morespecifically, to a transmitter configured to use an orthogonal frequencydivision multiplexing (OFDM) method, a receiver and a controlling methodthereof.

2. Description of the Related Art

Recent broadcasting communication services are developing to bemulti-functional using a high-quality broadband. Specifically, accordingto the development of the electronic technology, mobile broadcastingdevices such as high-definition digital TV and high-performance smartphone are widely distributed. Thus, requests for various broadcastingservices are growing.

For one example to follow these requests, broadcasting communicationstandards such as Digital Video Broadcasting the Second GenerationTerrestrial (DVB-T2) are developing. DVB-T2 is the second generationEuropean ground wave digital broadcasting standard which advancesperformance of DVB-T. DVB-T is selected to be a broadcasting standard inmore than 35 countries in the world including Europe. DVB-T2 implementsincreasing of a transmitting amount and higher bandwidth efficiency byapplying the latest technologies such as Low Density Parity Check (LDPC)codes and 256-QAM modulating method. Thereby, it has an advantage thathigh-quality of various services such as high0definition television(HDTV) can be provided within a limited bandwidth.

However, an OFDM system used in DVB-T2 may have a problem in which ahigh peak to average power ratio (PAPR) is generated due to modulationof multi-carrier waves. Thus, because the OFDM method transmits data byusing multi-carrier waves, a size of the amplitude of final OFDM signalsmay be a sum of amplitude value of each carrier wave. Thus, the finalOFDM signal may have great changes in the amplitude, or may have anextremely great value when phases of carrier waves are uniform to oneanother. Such high PAPR signals may be out of a linear operating rangeof a high power amplifier. Further, there may be a problem in which asystem performance deteriorates by generating distortion in signalspassing through the high power amplifier.

Various methods are being suggested in order to address the aboveproblem regarding the PAPR of the OFDM system. There are various PAPRreducing methods such as a clipping method, coding, selected mapping(SLM), a partial transmit sequence (PTS), and tone injection (TI).

In the TI method which is one of the above PAPR reducing methods, an Lnumber of tones are reserved among an N number of sub-carriers, and theL number of the reserved tones are used to reduce the PAPR withouttransmitting data.

FIG. 1 illustrates frame constitution regarding the related broadcastingcommunication system. A plurality of OFDM symbols constitute one frame,and the structure of pilots shows scattered constitution in whichpositions of the pilots change per OFDM symbol. Because the pilots areused to estimate channels, there should be no interference anddistortion. However, when the above reserved tones are used, a problemoccurs, in which the reserved tones collide with the pilots in the frameconstitution of FIG. 1.

FIG. 2 illustrates a case in which collision between the pilots and thereserved tone occurs according to the method using reserved tones amongthe related tone reserving methods in the frame constitution of FIG. 1.Thus, 201 does not show collision between the reserved tone and thepilots. However, 202, 203, 204 do show a collision between the pilotsand the reserved tone.

Thus, it is necessary to insert the reserved tones while avoidingcollision between the pilots and the reserved tones increases.

SUMMARY

Exemplary embodiments of the present inventive concept may overcome theabove disadvantages and other disadvantages not described above.However, the present inventive concept is not required to overcome thedisadvantages described above, and the exemplary embodiments of thepresent inventive concept may not overcome any of the problems describedabove.

One or more exemplary embodiments provide a transmitter configured toinsert and transmit reserved tones in a frame such that positions of thereserved tones do not overlap positions of pilots in a frame startingsymbol, at least one data symbol, and a frame closing symbol, areceiver, and a controlling method thereof.

According to an aspect of an exemplary embodiment, the transmitter mayinclude: a frame generator configured to generate a frame including aframe starting symbol, at least one data symbol and a frame closingsymbol; a pilot and reserved tone inserter configured to insert pilotsand reserved tones in at least one of the frame starting symbol, thedata symbol and the frame closing symbol such that positions of thereserved tones do not overlap positions of the pilots in the at leastone of the frame starting symbol, the data symbol and the frame closingsymbol; and a transmitter configured to transmit the frame in which thepilots and the reserved tones are inserted, wherein the reserved tonesare not used to transmit data in the frame.

Here, the pilot and reserved tone inserter may insert the pilots in thedata symbol according to a predetermined first arrangement pattern,insert the reserved tones in the data symbol such that the positions ofthe reserved tones do not overlap the positions of the pilots in thedata symbol, insert the pilots in the frame starting symbol and theframe closing symbol according to a predetermined second arrangementpattern, and insert the reserved tones in the frame starting symbol andthe frame closing symbol such that the positions of the reserved tonesdo not overlap the positions of the pilots in the frame starting symboland the frame closing symbol.

The predetermined second arrangement pattern may be determined based onthe predetermined first arrangement pattern.

The pilot and reserved tone inserter may insert a first reserved tone ina first data symbol among the at least one data symbol based on anarrangement pattern of the pilots inserted in the first data symbol, andinsert a second reserved tone in a second data symbol immediately nextto the first data symbol at a position shifted by a preset value from aposition of the first reserved tone in the first data symbol.

The transmitter may further include: an inverse fast Fourier transform(IFFT) calculator configured to perform an IFFT calculating on the framestarting symbol, the data symbol and the frame closing symbol in whichthe pilots and the reserved tones are inserted and output results of thecalculating; a parallel/series converter configured to convert parallelsignals output from the IFFT calculator into series signals and outputresults of the converting; and a PAPR reduction performer configured toreduce a PAPR based on the pilots and the reserved tones.

The PAPR reduction performer may calculate reducing amounts of the PAPRbased on the pilots and the reserved tones, adds the calculated reducingamounts to the series signals, and outputs results of the adding.

According to an aspect of another exemplary embodiment, the receiver mayinclude: a receiver configured to receive a frame comprising a framestarting symbol, at least one data symbol, and a frame closing symbol,wherein pilots and reserved tones are inserted at least one of the framestarting symbol, the data symbol and the frame closing symbol; and asignal processor configured to estimate channels based on the pilots andextract data by processing the frame starting symbol, the data symboland the frame closing symbol based on positions of the reserved tones,wherein the reserved tones are inserted such that position of thereserved tones do not overlap positions of the pilots, in the at leastone of the frame starting symbol, the data symbol and the frame closingsymbol, and wherein the reserved tones are not used to transmit the datain the frame.

According to an aspect of still another exemplary embodiment, thecontrolling method of the transmitter may include: generating a frameincluding a frame starting symbol, at least one data symbol, and a frameclosing symbol; inserting pilots and reserved tones in at least one ofthe frame starting symbol, the data symbol and the frame closing symbolsuch that positions of the reserved tones do not overlap positions ofthe pilots in the at least one of the frame starting symbol, the datasymbol and the frame closing symbol; and transmitting the frame in whichthe pilots and the reserved tones are inserted, wherein the reservedtones are not used to transmit data in the frame.

The inserting pilots and reserved tones may include: inserting thepilots in the data symbol according to a predetermined first arrangementpattern; inserting the reserved tones in the data symbol such that thepositions of the reserved tones do not overlap the positions of thepilots in the data symbol; inserting the pilots in the frame startingsymbol and the frame closing symbol according to a predetermined secondarrangement pattern; and inserting the reserved tones in the framestarting symbol and the frame closing symbol such that the positions ofthe reserved tones do not overlap the positions of the pilots in theframe starting symbol and the frame closing symbol.

The predetermined second arrangement pattern may be determined based onthe predetermined first arrangement pattern.

The inserting pilot tones and reserved tones may include: inserting afirst reserved tone in a first data symbol among the at least one datasymbol based on an arrangement pattern of the pilots inserted in thefirst data symbol; and inserting a second reserved tone in a second datasymbol immediately next to the first data symbol at a position shiftedby a preset value from a position of the first reserved tone in thefirst data symbol.

According to an aspect of still another exemplary embodiment, thecontrolling method of the receive may further include: performing anIFFT calculating on the frame starting symbol, the data symbol and theframe closing symbol in which the pilots and the reserved tones areinserted and outputting results of the calculating; converting parallelsignals output by the performing the IFFT into series signals andoutputting results of the converting; and reducing a PAPR based on thepilots and the reserved tones.

The reducing a PAPR may include calculating reducing amounts of the PAPRbased on the pilots and the reserved tone, adding the calculatedreducing amounts to the series signals, and outputting results of theadding.

According to an aspect of still another exe embodiment, the controllingmethod of the receiver includes: receiving a frame comprising a framestarting symbol, at least one data symbol, and a frame closing symbol,wherein pilots and reserved tones are inserted at least one of the framestarting symbol, the data symbol and the frame closing symbol; andestimating channels based on the pilots and extract data by processingthe frame starting symbol, the data symbol and the frame closing symbolbased on positions of the reserved tones, wherein the reserved tones areinserted such that position of the reserved tones do not overlappositions of the pilots, in the at least one of the frame startingsymbol, the data symbol and the frame closing symbol, and wherein thereserved tones are not used to transmit the data in the frame.

According to the above various exemplary embodiments, the reserved tonescan be inserted while avoiding collision between the pilots and thereserved tones, and the PAPR can be reduced based on the inserted pilotsand reserved tones.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the present inventive concept will bemore apparent by describing certain exemplary embodiments with referenceto the accompanying drawings, in which:

FIGS. 1 and 2 illustrate a related art frame;

FIG. 3 is a block diagram of a transmitter according to an exemplaryembodiment;

FIG. 4 illustrates frame constitution according to an exemplaryembodiment;

FIG. 5 illustrates positions of scattered pilots inserted into a framestarting symbol, a data symbol, and a frame closing symbol, according toan exemplary embodiment;

FIG. 6 illustrates frame constitution inserted such that scatteredpilots do not collide with reserved tones, according to an exemplaryembodiment;

FIG. 7 illustrates an arrangement pattern of scattered pilots which areshifted and arranged by a preset value, according to an exemplaryembodiment;

FIG. 8 is a detailed block diagram of a transmitter according to anexemplary embodiment;

FIG. 9 is a detailed block diagram of a PAPR reduction performeraccording to an exemplary embodiment;

FIG. 10 is a block diagram of a receiver according to an exemplaryembodiment;

FIG. 11 is a detailed block diagram of a signal processor according toan exemplary embodiment;

FIG. 12 is a flowchart provided to explain a controlling method of atransmitter, according to an exemplary embodiment; and

FIG. 13 is a flowchart provided to explain a controlling method of areceiver, according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Certain exemplary embodiments of the present inventive concept will nowbe described in greater detail with reference to the accompanyingdrawings.

In the following description, same drawing reference numerals are usedfor the same elements even in different drawings. The matters defined inthe description, such as detailed construction and elements, areprovided to assist in a comprehensive understanding of the presentinventive concept. Accordingly, it is apparent that the exemplaryembodiments of the present inventive concept can be carried out withoutthose specifically defined matters. Also, well-known functions orconstructions are not described in detail since they would obscure theinvention with unnecessary detail.

Referring to constitution, the pilots in FIG. 2 includes continualpilots that continue over a plurality of OFDM symbols and scatteredpilots that are generated on one OFDM symbol and distributed on thefrequency domain. Because positions of the pilots are different per OFDMsymbol in this frame constitution, positions of reserved tones should bedifferent for the frame constitute of FIG. 2. Thus, each OFDM symbolshould include different reserved tones.

However, if each OFDM symbol includes different reserved tones, impulsewave shapes generated by the reserved tones provide different signals.Therefore, the OFDM system having the frame constitution of FIG. 2should store information regarding every impulse wave shape in a memory,and a memory size increases.

According to an exemplary embodiment, there is provided a method inwhich one type of reserved tones is used for each frame withoutproviding different types of reserved tones in each OFDM symbol. Theframe constitution of the scattered pilots in FIG. 2 shows that thepilots move at a certain interval in each OFDM symbol. When thepositions of the reserved tones are moved at the uniform or sameinterval with respect to those of the scattered pilots based on theabove features, collision between the reserved tones and the scatteredpilots can be avoided.

FIG. 3 is a block diagram of a transmitter according to an exemplaryembodiment.

Referring to FIG. 3, the transmitter 300 includes a frame generator 310,a pilot and reserved tone inserter 320 and a transmitting unit 330.

The frame generator 310 may generate a frame which includes a framestarting symbol, a data symbol and a frame closing symbol.

The frame according to the present embodiment has a frame structureaccording to an Advanced Television System Committee (ATSC) 3.0 system.Specifically, the frame will be explained below by referring to FIG. 4.

FIG. 4 illustrates constitution of the frame according to the presentembodiment.

Referring to FIG. 4, one frame 400 includes one preamble symbol 440, oneframe starting symbol 410, a plurality of data symbols 420 and one frameclosing symbol 430.

Herein, the frame 400 may correspond to a frame used in DVB-T2, which isa T2 frame. Thus, constitution of the T2 frame of DVB-T2 will bespecifically described below in relation to the present embodiment.

One T2 frame includes a P1 preamble symbol informing a start position ofthe frame, a P2 preamble symbol transmitting L1 signals, and datasymbols transmitting broadcasting signals.

Specifically, the P1 preamble symbol may be positioned at a front of theT2 frame and used to extract a start point of the T2 frame. Here, the P1preamble symbol, which uses a 1K Fast Fourier Transform (FFT) size, isthe signal in a guard interval format. Further, the P1 preamble symbolon the frequency domain may transmit seven (7) bits of information byusing 384 sub-carriers among 853 sub-carriers of 1K FFT.

The preamble symbol 440 according to the present embodiment maycorrespond to the above described P1 preamble symbol and P2 preamblesymbol, may be used to inform a start position of a frame for performingsynchronization, and further may transmit L1 signals to be used forextracting data from broadcasting signals.

The frame starting symbol 410 informs a start point of the data symbol420, and positions of pilots and reserved tones which are inserted intothe frame starting symbol 410 and the data symbol 420 are different. Itwill be further described below.

The pilot and reserved tone inserter 320 may insert the pilots into theframe starting symbol, the data symbol, and the frame closing symbol,and insert the reserved tones so as not to overlap the positions of thepilots.

Herein, the pilot and reserved tone inserter 320 may correspond to apilot inserter in a DVB-T2 transmitting system. The DVB-T2 transmittingsystem may include an input processor (not illustrated), a bitinterleaved coding and modulation (BICM) encoder (not illustrated), aframe builder (not illustrated), and a modulator (not illustrated).

The above units will be briefly explained because they are uniformlydefined in DVB-T2 which is one of digital broadcasting standards. Referto “Digital Video Broadcasting (DVB); Frame structure channel coding andmodulation for a second generation digital terrestrial televisionbroadcasting system (DVB-T2)” for the detailed descriptions.

The input processor (not illustrated) may perform signal processing suchthat a baseband frame format of signals can be generated from inputbroadcasting signals.

The BICM encoder (not illustrated) performs coding by determining aforward error correction (FEC) coding rate and constellation orderaccording to an area where data to be served will be transmitted (fixedPHY frame or mobile PHY frame). Signaling information regarding data tobe served may be coded through another BICM encoder (not illustrated) orby sharing the data to be served with the above BICM encoder (notillustrated) according to implementation.

The frame builder (not illustrated) and the modulator (not illustrated)constitute a frame by determining OFDM parameters regarding a signalingarea and OFDM parameters regarding the area where data to be served willbe transmitted, and generate the frame by adding a sync area. Further,the frame builder (not illustrated) and the modulator (not illustrated)perform a modulation to modulate the generated frame into RF signals,and transmit the RF signals to a receiver.

Herein, a T2 frame structure may be constituted with data sub-carrierwaves to transmit the modulated signals from broadcasting signals,pilots to estimate channels, and reserved tones to reduce a PAPR.

The pilots and the reserved tones may be processed in the pilot inserter(not illustrated) of the modulator (not illustrated). Specifically, thepilot inserter (not illustrated) inserts pilots in a predetermined pilotpattern on corresponding positions within the frame, and outputs to anOFDM generator (not illustrated). A plurality of cells within an OFDMframe are modulated into reference information regarding transmittingvalues informed to the receiver. Cells including the referenceinformation are transmitted at a boosted power level. The informationtransmitted from the cells are a scattered pilot cell, a continual pilotcell, an edge pilot cell, a P2 pilot cell, or a frame closing pilotcell. Values of pilot information are obtained from a reference sequencewhich is a series of values.

Further, the pilot and reserved tone inserter 320 according to thepresent embodiment may correspond to the modulator (not illustrated) andthe pilot inserter (not illustrated) used in DVB-T2.

Further, the transmitter 330 may transmit a frame inserted with thepilot and the reserved tone.

Meanwhile, the pilot and reserved tone inserter 320 inserts pilots forchannel estimation and synchronization. The pilots may be divided into aP2 pilot only included in a P2 symbol and a frame closing pilot of theframe closing symbol as well as a scattered pilot and a continual pilot.

The scattered pilot is a pilot inserted in a predetermined pattern inthe frequency axis direction as well as the time axis direction, andused mainly for channel estimation and equalization. Although thescattered pilot pattern of DVB-T is uniformly inserted regardless of anFFT size or protecting section, DVB-T2 flexibly applies eight (8)patterns from PP1 to PP8 according to FFT and protecting section. Thesepatterns are established according to the length (1/Dx) of the maximumprotecting section and limitation (1/Dy) of channel Doppler. Becausesizes of the pilots per pattern are greater than normal data up to2.5-7.4 dB, the patterns have an advantage in that overhead according toinserting the pilot can be reduced while maintaining sufficientperformance of channel estimation.

Further, the continual pilot is inserted in a predetermined pattern inthe time axis direction, and sizes of the inserted pilots are greaterthan normal data by 2.5-8.5 dB according to FFT while a number of theinserted pilots is smaller compared to DVB-T. Thus, it reduces overheadaccording to inserting the pilots at 8K, 16K, 32K modes from 2.5% to0.7% without deteriorating in synchronizing frequencies with thecontinual pilots and performance of extracting CPE, and further reducesoverhead by sharing positions of the scattered pilots with somecontinual pilots.

The continual pilots according to the present embodiment include pilotswhich are consecutively inserted in the frame starting symbol 410, thedata symbol 420, and the frame closing symbol 430 while their positionsare not modified therein, and the scattered pilots include pilots whosepositions are modified and inserted according to a predetermined patternin the frame starting symbol 410, the data symbol 420, and the frameclosing symbol 430.

FIG. 5 illustrates positions of the scattered pilots which are insertedin a frame starting symbol (FSS) 410, the data symbol 420, and the frameclosing symbol (FCS) 430, according to an exemplary embodiment.

For example, when a pilot pattern is P4, 4, the scattered pilotsinserted in the data symbol 420 are determined to be arranged with apattern of Dx=4 and Dy=4. This indicates that the scattered pilotsinserted in the data symbol 420 are shifted by a uniform interval offour (4) and arranged in four (4) columns.

Further, the scattered pilots inserted in the frame starting symbol 410and the frame closing symbol 430 are determined to be arranged with apattern of Dx=4, Dy=1. This indicates that the scattered pilots insertedinto the frame starting symbol 410 and the frame closing symbol 430 areshifted by a uniform interval of four (4) and arranged in one (1)column.

Thus, the arrangement pattern of the scattered pilots inserted in thedata symbol 420 is different from the arrangement pattern of thescattered pilots inserted in the frame starting symbol 410 and the frameclosing symbol 430.

Therefore, the arrangement pattern of reserved tones inserted in thedata symbol 420 is different from the arrangement pattern of thereserved tones inserted in the frame starting symbol 410 and the frameclosing symbol 430 to each other.

Further, the pilot and reserved tone inserter 320 may insert pilots inthe data symbol 420 according to a predetermined first arrangementpattern, and insert reserved tones so as not to overlap the positions ofthe pilots in the data symbol 420. The pilot and reserved tone inserter320 may also insert pilots into the frame starting symbol 410 and theframe closing symbol 430 according to a predetermined second arrangementpattern, and insert reserved tones so as not to overlap the positions ofthe pilots in the frame starting symbol 410 and the frame closing symbol430.

Herein, the predetermined second arrangement pattern is determined basedon the predetermined first arrangement pattern. Thus, the predeterminedfirst arrangement pattern may indicate an arrangement pattern of thescattered pilots inserted in the data symbol 420, and the predeterminedsecond arrangement pattern may indicate an arrangement pattern of thescattered pilots inserted in the frame starting symbol 410 and the frameclosing symbol 430.

Further, the predetermined first arrangement pattern and thepredetermined second arrangement pattern may be arrangement patternsincluding arrangement of the continual pilots as well as arrangement ofthe scattered pilots. The reserved tones inserted in the frame startingsymbol 410, the data symbol 420, and the frame closing symbol 430 shouldnot overlap the positions of the continual pilots and the scatteredpilots.

Thus, according to the predetermined first arrangement pattern, thepilot and reserved tone inserter 320 may insert reserved tones in thedata symbol 420 so as not to overlap the scattered pilots and thecontinual pilots inserted in the data symbol 420. Also, according to thepredetermined second arrangement pattern, the pilot and reserved toneinserter 320 may insert reversed tones in the frame starting symbol 410and the frame closing symbol 430 so as not to overlap the scatteredpilots and the continual pilots inserted in the frame starting symbol410 and the frame closing symbol 430.

If the first arrangement pattern and the second arrangement pattern onlyinclude the arrangement pattern of the scattered pilots, reserved tonesmay be inserted by further considering the arrangement pattern of thecontinual pilots. If the first arrangement pattern and the secondarrangement pattern include the arrangement patterns of the scatteredpilots and the continual pilots, reserved tones may be inserted byconsidering only the first and the second arrangement patterns.

FIG. 6 illustrates a frame constitution in which scattered pilots andreserved tones are inserted so as not to collide with each other.

As described above, collision between the scattered pilots and thereserved tones can be avoided and a problem in increasing the size of amemory when one reserved tone is reused can be addressed by determiningthe positions of the reserved tones in OFDM symbols to be the same asthe shift intervals of the scattered pilots.

If the positions of the reserved tones circularly shift in the frequencydomain, the wave shapes of an impulse generated by the reserved tonesshow changes only in phases while complex values do not change. Becausesuch changes in phases become different by displaced intervals, ifinitial phase information is obtained, the phase changes may beconfirmed according to the displaced intervals. Thus, the methodinserting the reserved tones by considering the arrangement pattern ofthe pilots according to the present embodiment may be applied to everyOFDM symbol within a frame.

Referring to FIG. 6, the arrangement patterns of pilots inserted in aframe starting symbol 610 and a frame closing symbol 630 are uniform orsame, and the arrangement patterns of reserved tones inserted so as notto overlap the arrangement patterns of the pilots are uniform or same.

Meanwhile, the arrangement pattern of pilots inserted in a data symbol620 is different from the arrangement patterns of pilots inserted in theframe starting symbol 610 and the frame closing symbol 630. Thearrangement pattern of reserved tones inserted in the data symbol 620 soas not to overlap the arrangement pattern of the pilots in the datasymbol 620 is different from the arrangement pattern of reserved tonesinserted in the frame starting symbol 610 and the frame closing symbol630.

Further, the pilots and the reserved tones inserted in all the symbols610, 620, 630 described in FIG. 6 do not overlap with one another.

Meanwhile, the arrangement pattern of the pilots inserted in the framestarting symbol 610 and the frame closing symbol 630 may be determinedbased on the arrangement pattern of the pilots inserted in the datasymbol 620.

For example, when an arrangement pattern of pilots inserted in the datasymbol 620 is Dx=4, Dy=4, an arrangement pattern of pilots inserted inthe frame starting symbol 610 and the frame closing symbol 630 becomesDx=4, Dy=1. Thus, this (Dx=4, Dy=1) indicates that the pilots arearranged in one (1) column while the same shift interval of the insertedpilots maintained.

Thus, the pilots inserted in the frame starting symbol 610 and the frameclosing symbol 630 are arranged on all positions of sub-carrierscorresponding to the arrangement pattern of the pilots inserted in thedata symbol 620.

Meanwhile, the pilot and reserved tone inserter 320 may insert a firstreserved tone based on the arrangement pattern of the pilots inserted inthe data symbol 620, and additionally insert a second reserved tone at aposition shifted by a preset value from the position of the firstreserved tone.

Specifically, as described above, the pilot and reserved tone inserter320 may reserve the first reserved tone so as not to overlap thepositions of the pilots inserted in the data symbol 620. Herein, theinserted pilots indicate all the scattered pilots and the continualpilots. Thus, the pilot and reserved tone inserter 320 may reserve thefirst reserved tone so as not to overlap positions of the scatteredpilots and the continual pilots which are inserted in the data symbol620.

Further, the pilot and reserved tone inserter 320 may reserve the secondreserved tone by additionally considering the arrangement pattern of thescattered pilots. Specifically, the pilot and reserved tone inserter 320may reserve the second reserved tone by considering the shift amount ofthe scattered pilots. This relationship between the pilots and thereserved tones will be described by referring to FIG. 7.

FIG. 7 illustrates an arrangement pattern of scattered pilots which areshifted by a preset value and arranged, according to an exemplaryembodiment.

Referring to FIG. 7, when the scattered pilots are positioned at a 20sub-carrier interval, the scattered pilots circularly shift by a four(4) sub-carrier interval as OFDM symbols increase.

Thus, the pilot and reserved tone inserter 320 may insert the firstreserved tone so as not to overlap the scattered pilots inserted in asecond column of FIG. 7. Because the scattered pilots inserted in afirst column of FIG. 7 are shifted by the four (4) sub-carrier intervalbased on the scattered pilots inserted in the second column, the pilotand reserved tone inserter 320 may insert the second reserved tone at aposition shifted by the four (4) sub-carrier interval from the positionof the first reserved tone inserted in the second column.

A following mathematical equation 1 may be used to determine a positionof a reserved tone in an OFDM symbol by considering the arrangementpattern of the scattered pilots described above.

S ₁ ={i _(k) +D _(X)*(1 mod D _(Y))|i _(n) ∈S ₀,0≤n<N _(RT) ,N _(P)≤1<N_(P) +L _(normal)  (1),

where S0 indicates a position of a reserved tone and NRT indicates anumber of reserved tones.

Thus, the pilot and reserved tone inserter 320 may be configured todetermine only position of the first reserved tone without a necessityto calculate positions of a reserved tone with respect to all datasymbols. The pilot and reserved tone inserter 320 may only determineposition of the second reserved tone by considering a shift value of thescattered pilots across columns. Therefore, a calculating amount can bereduced, and a memory size storing impulse signals corresponding to eachreserved tone can be reduced, as described above.

Meanwhile, reserved tones inserted in the frame starting symbol 610 andthe frame closing symbol 630 may be determined according to Table 1below, according to an exemplary embodiment.

TABLE 1 FFT (# of Reserved tones) Reserved Tone Indices FSS, FCS Symbol8k (72) 151, 313, 387, 763, 809, 925, 1097, 1219, 1265, 1406, 1451,1485, 1867, 1897, 1935, 1941, 2147, 2243, 2265, 2374, 2433, 2490, 2507,2513, 2550, 2559, 2679, 2698, 3079, 3106, 3225, 3281, 3334, 3626,3750,3814, 3953, 4038, 4158, 4179, 4205, 4238, 4298, 4357, 4591, 4669,4691, 4726, 4982, 4999, 5058, 5169,5206, 5211, 5222, 5310, 5411, 5423,5521, 5693, 5813, 5866, 5877, 5883, 5950, 6035, 6043, 6150, 6249,6446,6467, 6489 16k (144) 202, 395, 539, 771, 799, 845, 921, 1003, 1103,1413, 1462, 1505, 1647, 1701, 1734, 1823, 1861, 1873, 1894, 2165, 2369,2374, 2613, 2675, 2698, 2877, 3178, 3201, 3217, 3390, 3434, 3454, 3737,3958, 3986, 4033, 4107, 4579, 4721, 4729, 4766, 4783, 4795, 4833, 5025,5267, 5354, 5522, 5543, 5739, 5789, 5874, 5989, 6187, 6254, 6314, 6567,6575, 6749, 6775, 6783, 6938, 7009, 7121, 7125, 7215, 7353, 7514, 7522,7574, 7594, 7902, 7955, 8190, 8230, 8318, 8338, 8527, 8554, 8715, 8757,8781, 8913, 8994, 9195, 9298, 9306, 9534, 9549, 9586, 9697, 9709, 9761,9905, 10001, 10047, 10382, 10474, 10535, 10587, 10671, 10707, 10829,11051, 11073, 11079, 11143, 11257, 11395, 11405, 11467, 11571, 11594,11931, 11961, 11993, 12022, 12135, 12245, 12430, 12443, 12507, 12526,12631, 12690, 12813, 12819, 12843, 12918, 12953, 13029, 13059, 13067,13071, 13157, 13378, 13402, 13441, 13466, 13554, 13590, 13662, 13705,13747 32k (288) 145, 156, 395, 467, 492, 519, 537, 598, 604, 633, 650,706, 753, 1075, 1171, 1365, 1369, 1499, 1590, 1606, 1957, 2074, 2249,2357, 2359, 2417, 2471, 2493, 2547, 2675, 2734, 2828, 2932, 2981, 3017,3110, 3122, 3356, 3607, 3707, 3754, 3758, 3895, 3978, 4329, 4346, 4509,4556, 5218, 5220, 5247, 5329, 5475, 5500, 5577, 5631, 5909, 5954, 5998,6007, 6010, 6020, 6166, 6167, 6196, 6206, 6243, 6279, 6485, 6666, 6669,6827, 7563, 7565, 7833, 7901, 8050, 8074, 8349, 8380, 8467, 8711, 8732,8779, 8869, 8963, 8997, 9114, 9166, 9491, 9524, 9571, 9578, 9597, 9598,9643, 9657, 9659, 9751, 9827, 10259, 10295, 10305, 10439, 10606, 10627,10663, 10748, 10891, 11249, 11279, 11386, 11419, 11437, 11538, 11665,12069, 12082, 12134, 12218, 12266, 12291, 12329, 12474, 12617, 12654,12878, 13547, 13566, 13567, 13574, 13641, 13771, 13798, 13935, 14092,14167, 14292, 14346, 14351, 14474, 14524, 14673, 14690, 14774, 14787,14810, 14815, 14841, 14935, 14965, 15118, 15353, 15428, 15455, 15558,15697, 15710, 15723, 15843, 15886, 15891, 15925, 16044, 16105, 16234,16261, 16534, 16621, 16634, 17044, 17059, 17206, 17317, 17379, 17489,17689, 18083, 18270, 18374, 18539, 18588, 18683, 18701, 18734, 18739,18826, 18827, 18993, 19039, 19245, 19265, 19269, 19287, 19301, 19494,19673, 19885, 19909, 20108, 20212, 20359, 20371, 20372, 20426, 20439,20516, 20692, 20727, 20729, 20847, 20886, 20919, 20961, 20967, 20982,21276, 21439, 21727, 21781, 21910, 22396, 22407, 22463, 22529, 22562,22581, 22687, 22870, 22938, 23147, 23263, 23460, 23566, 23637, 23747,23978, 24058, 24116, 24201, 24258, 24372, 24379, 24423, 24492, 24583,24826, 24908, 25137, 25281, 25285, 25343, 25366, 25518, 25770, 25780,25787, 25814, 26010, 26046, 26100, 26169, 26233, 26257, 26307, 26322,26361, 26452, 26469, 26490, 26501, 26580, 26629, 26662, 26681, 26756,26858, 26990, 27006, 27061, 27189, 27252, 27308, 27421, 27433, 27539,27625, 27694

Table 1 shows indices which mark positions of reserved tones inserted inthe frame starting symbol and the frame closing symbol, according to anexemplary embodiment. The positions of the reserved tones in Table 1 arepositions of the reserved tones in the frame starting symbol 610 and theframe closing symbol 630 which are determined by considering thepositions of the scattered pilots and the continual pilots according tomodes, i.e., modes of FFT sizes which are 8K, 16K and 32K.

Meanwhile, DVB-T2 considers various FFT sizes of OFDM, which are 1K, 2K,4K, 8K, 16K and 32K modes, described below. Table 2 below shows a numberof sub-carriers, a number of data symbols and a number of reserved tonesat each mode of the FFT size, according to an exemplary embodiment.

TABLE 2 1K mode 2K mode 4K mode 8K mode 16K mode 32K mode Number of 10242048 4096 8192 16384 32766 Sub-carriers Number of 853 1705 3409 651713833 27265 Data Symbols Number of 9 18 36 72 144 288 Reserved Tones

In Table 2, the number of reserved tones that can be inserted andinserting positions may be different according to the FFT size mode. Thescattered pilots may be inserted in various modified formats accordingto the above modes, which may be similar to the arrangement pattern ofFIG. 7. However, differently from FIG. 7, the scattered pilots may beinserted at a 12 sub-carrier interval. Further, reserved tones may beinserted so as not to overlap the inserting positions of the scatteredpilots. Therefore, a number of reserved tones that can be inserted ineach mode and inserting positions become different.

Like reserved tones differently inserted according to each of the abovemodes, reserved tones inserted into the frame starting symbol and theframe closing symbol may be differently inserted according to each mode,according to an exemplary embodiment.

Table 3 below summarizes a number of sub-carriers and a number ofreserved tones inserted according to each mode of Table 1.

TABLE 3 8K mode 16K mode 32K mode Number of Sub-carriers 8192 1638432766 Number of Reserved Tones 72 144 288

In reference to Table 1, indices marked in modes indicate positions ofthe reserved tones inserted into the frame starting symbol 610 and theframe closing symbol 630.

Table 1 further shows that that the positions of the reserved tones aredifferent according to the modes.

Meanwhile, reserved tones inserted in the data symbol may be determinedaccording to Table 4 below, according to an exemplary embodiment.

TABLE 4 FFT (# of Reserved tones) Reserved Tone Indices Data Symbol 8k(72) 67, 100, 152, 203, 247, 267, 579, 696, 826, 915, 1017, 1023, 1097,1245, 1289, 1436, 1452, 1476, 1564, 1575, 1614, 1733, 1773, 1916, 2212,2333, 2372, 2466, 2565, 2679, 2722, 2779, 2791, 2911, 2935, 2964, 3205,3246, 3367, 3466, 3544, 3710, 3740, 3751, 3828, 3835, 4002, 4175, 4212,4645, 4649, 4662, 4933, 5027, 5274, 5496, 5588, 5597, 5690, 5719, 5737,5897, 6053, 6180, 6277, 6372, 6388, 6447, 6529, 6606, 6735, 6758 16k(144) 130, 237, 310, 358, 395, 635, 838, 1074, 1098, 1103, 1143, 1178,1182, 1257, 1265, 1314, 1450, 1471, 1702, 1724, 1826, 1950, 1953, 1997,2111, 2115, 2180, 2278, 2572, 2577, 2667, 2811, 2889, 2916, 2926, 3175,3245, 3387, 3453, 3526, 3541, 3700, 3735, 3787, 4018, 4053, 4126, 4317,4421, 4479, 4485, 4553, 4675, 4690, 4949, 4990, 5151, 5288, 5289, 5334,5626, 5752, 5800, 5868, 6015, 6023, 6075, 6127, 6316, 6392, 6566, 6664,6712, 6750, 6772, 6796, 6916, 7159, 7275, 7405, 7460, 7661, 7676, 7846,7944, 8026, 8175, 8254, 8328, 8350, 8478, 8648, 8754, 8772, 8852, 9110,9282, 9397, 9403, 9414, 9449, 9481, 9570, 9596, 9606, 9863, 9974, 9982,10031, 10206, 10275, 10285, 10340, 10403, 10604, 10778, 10974, 11058,11094, 11097, 11754, 11810, 11889, 12008, 12011, 12152, 12199, 12343,12407, 12418, 12993, 13094, 13110, 13114, 13137, 13164, 13338, 13415,13480, 13575, 13652, 13687, 13716, 13729 32k (288) 56, 126, 142, 154,238, 243, 278, 387, 429, 481, 507, 555, 575, 689, 699, 918, 940, 1052,1082, 1263, 1507, 1548, 1585, 1601, 1608, 1628, 1741, 1771, 1791, 2140,2223, 2334, 2513, 2630, 2657, 2669, 2722, 2869, 2963, 3092, 3183, 3363,3370, 3457, 3473, 3604, 3830, 3959, 4079, 4501, 4642, 4662, 4665, 4709,5178, 5215, 5298, 5507, 5643, 5708, 5738, 5747, 5755, 5788, 5867, 5932,5961, 6070, 6153, 6171, 6182, 6296, 6340, 6366, 6413, 6428, 6494, 6639,6955, 7026, 7027, 7292, 7406, 7612, 8234, 8243, 8252, 8257, 8287, 8525,8588, 8846, 8921, 9012, 9209, 9276, 9371, 9683, 9864, 9913, 9971, 10007,10008, 10011, 10314, 10411, 10442, 10452, 10538, 10563, 10743, 10748,10814, 10925, 11282, 11332, 11448, 11630, 11711, 11714, 11866, 11898,12022, 12027, 12165, 12196, 12269, 12371, 12697, 12938, 12994, 13044,13116, 13153, 13175, 13186, 13314, 13398, 13515, 13640, 13660, 13698,13774, 13916, 14153, 14357, 14362, 14697, 14717, 14938, 15038, 15070,15101, 15121, 15143, 15157, 15283, 15284, 15302, 15586, 15677, 15681,15742, 15991, 16067, 16200, 16254, 16290, 16419, 16615, 16621, 16825,16868, 17091, 17098, 17115, 17350, 17403, 17478, 17484, 17542, 17640,17677, 17870, 17969, 18006, 18289, 18491, 18663, 18675, 18703, 18741,18788, 18841, 18990, 19193, 19310, 19422, 19522, 19532, 19537, 19675,19702, 19832, 19976, 20150, 20186, 20318, 20472, 20613, 20616, 20621,20622, 20634, 20737, 20886, 20921, 20999, 21089, 21317, 21527, 21751,21874, 21959, 22052, 22121, 22191, 22331, 22458, 22538, 22548, 22692,22767, 22793, 22837, 22888, 22905, 22916, 23004, 23059, 23423, 23476,23505, 23507, 23528, 23567, 23626, 23773, 24065, 24183, 24332, 24920,24953, 25249, 25298, 25484, 25514, 25547, 25604, 25638, 25701, 25785,25812, 25895, 26015, 26203, 26226, 26267, 26293, 26327, 26364, 26444,26467, 26602, 26657, 26697, 26941, 26984, 27069, 27140, 27160, 27208,27224, 27236, 27492, 27505, 27671, 27677

Table 4 shows indices which mark positions of reserved tones inserted inthe data symbol 620, according to an exemplary embodiment. The positionsof the reserved tones illustrated in Table 4 are determined byconsidering inserting positions of the scattered pilots and thecontinual pilots according to modes of FFT sizes which are 8K, 16K and32K.

Like reserved tones differently inserted according to the above modes,reserved tones inserted in the data symbol may be differently insertedaccording to the modes, according to an exemplary embodiment.

Table 5 below summarizes a number of sub-carriers and a number ofreserved tones inserted according to the modes of FIG. 4.

TABLE 5 8K mode 16K mode 32K mode Number of Sub-carriers 8192 1638432766 Number of Reserved Tones 72 144 288

In reference to Table 4, indices marked in the modes indicate positionsof the reserved tones inserted in the data symbol 620. Likewise,positions of the reserved tones marked in the modes are different fromone another.

Meanwhile, pilots may be inserted at positions as shown in Table 6below, according to an exemplary embodiment.

TABLE 6 FFT (# of Reserved tones) Continual pilot Indices 8k (90) 9, 25,41, 154, 173, 301, 357, 477, 505, 609, 645, 761, 805, 909, 941, 1067,1098, 1199, 1225, 1347, 1397, 1487, 1514, 1633, 1669, 1797, 1822, 1925,1961, 2089, 2119, 2226, 2245, 2387, 2423, 2546, 2587, 2667, 2709, 2835,2861, 2993, 3026, 3146, 3189, 3290, 3318, 3473, 3510, 3651, 3683, 3811,3861, 3991, 4045, 4137, 4163, 4265, 4297, 4417, 4457, 4569, 4598, 4733,4769, 4901, 4942, 5073, 5113, 5253, 5289, 5389, 5413, 5539, 5585, 5714,5755, 5847, 5873, 6010, 6045, 6175, 6207, 6342, 6379, 6482, 6525, 6649,6675, 6862 16k (180) 18, 31, 50, 66, 82, 243, 307, 331, 346, 517, 602,671, 714, 861, 953, 987, 1010, 1157, 1217, 1263, 1290, 1429, 1522, 1563,1610, 1753, 1818, 1851, 1881, 2061, 2133, 2167, 2197, 2301, 2399, 2430,2450, 2647, 2694, 2763, 2794, 2899, 2973, 3003, 3027, 3159, 3267, 3302,3338, 3497, 3593, 3617, 3645, 3793, 3851, 3895, 3923, 4059, 4179, 4213,4239, 4409, 4451, 4475, 4490, 4647, 4774, 4821, 4847, 5013, 5093, 5142,5175, 5277, 5333, 5383, 5419, 5577, 5671, 5701, 5723, 5895, 5987, 6025,6051, 6222, 6291, 6331, 6378, 6497, 6579, 6609, 6637, 6818, 6946, 6983,7021, 7201, 7303, 7343, 7366, 7525, 7621, 7683, 7721, 7895, 7983, 8046,8090, 8199, 8274, 8307, 8325, 8449, 8531, 8569, 8593, 8743, 8835, 8885,8915, 9055, 9137, 9171, 9197, 9367, 9466, 9498, 9539, 9723, 9801, 9843,9885, 10058, 10147, 10190, 10226, 10391, 10506, 10545, 10578, 10703,10779, 10802, 10825, 10959, 11077, 11133, 11169, 11326, 11429, 11479,11510, 11629, 11694, 11721, 11747, 11941, 12021, 12063, 12089, 12243,12350, 12383, 12414, 12598, 12685, 12715, 12758, 12881, 12963, 13013,13050, 13195, 13297, 13325, 13349, 13517, 13725, 13821 32k (360) 35, 45,61, 82, 99, 117, 131, 147, 163, 290, 486, 605, 614, 635, 662, 685, 691,858, 1033, 1187, 1203, 1269, 1341, 1379, 1427, 1582, 1721, 1881, 1906,1925, 1973, 2006, 2019, 2217, 2314, 2425, 2434, 2478, 2526, 2549, 2579,2709, 2857, 3009, 3043, 3083, 3125, 3173, 3219, 3399, 3506, 3621, 3635,3674, 3701, 3749, 3762, 3997, 4122, 4257, 4266, 4298, 4333, 4382, 4393,4539, 4601, 4786, 4797, 4831, 4859, 4881, 4899, 5095, 5293, 5378, 5387,5473, 5525, 5553, 5587, 5693, 5797, 5937, 5946, 5989, 6005, 6037, 6054,6139, 6317, 6501, 6533, 6558, 6603, 6654, 6675, 6807, 6994, 7163, 7186,7213, 7233, 7277, 7289, 7467, 7586, 7689, 7701, 7753, 7790, 7813, 7845,8011, 8117, 8337, 8357, 8389, 8425, 8461, 8477, 8665, 8817, 8893, 8902,8922, 8949, 8973, 8979, 9177, 9293, 9539, 9547, 9590, 9641, 9679, 9693,9885, 10026, 10151, 10185, 10214, 10283, 10341, 10349, 10471,10553,10646, 10666, 10721, 10766, 10797, 10837, 10977, 11153, 11325, 11341,11378, 11401, 11431, 11445, 11605, 11789, 11939, 11973, 11994, 12049,12070, 12102, 12253, 12443, 12557, 12582, 12619, 12662, 12717, 12755,12866, 12993, 13150, 13158, 13205, 13217, 13254, 13273, 13445, 13635,13846, 13891, 13907, 13965, 14002, 14041, 14225, 14402, 14571, 14605,14637, 14685, 14714, 14731, 14917, 15050, 15209, 15242, 15282, 15365,15390, 15442, 15622, 15790, 15953, 15965, 16055, 16091, 16163, 16179,16239, 16397, 16533, 16547, 16577, 16613, 16630, 16650, 16750, 16897,17045, 17061, 17089, 17137, 17173, 17186, 17351, 17485, 17637, 17669,17695, 17770, 17793, 17829, 17939, 18109, 18246, 18274, 18306, 18341,18365, 18393, 18566, 18733, 18901, 18931, 18969, 18997, 19049, 19077,19253, 19445, 19589, 19603, 19653, 19686, 19741, 19769, 19989, 20115,20275, 20293, 20357, 20379, 20437, 20451, 20675, 20781, 20989, 21011,21050, 21090, 21149, 21155, 21279, 21405, 21537, 21557, 21577, 21603,21634, 21650, 21789, 21917, 22133, 22154, 22197, 22266, 22323, 22338,22489, 22651, 22823, 22857, 22914, 22958, 22979, 23019, 23205, 23258,23361, 23387, 23406, 23441, 23474, 23493, 23685, 23881, 24007, 24041,24069, 24125, 24149, 24178, 24317, 24486, 24689, 24699, 24739, 24765,24813, 24827, 25061, 25195, 25331, 25369, 25385, 25430, 25485, 25515,25649, 25761, 25894, 25926, 25981, 26025, 26089, 26099, 26246, 26390,26569, 26594, 26621, 26650, 26674, 26698, 26910, 27033, 27241, 27449,27511, 27642, 27801

Table 6 shows indices which mark inserting positions of the continualpilots according to the modes of FFT sizes which are 8K, 16K and 32K,according to an exemplary embodiment.

The indices marking positions of the reserved tones inserted in theframe starting symbol 610, the frame closing symbol 630 and the datasymbol 620, as shown in Tables 1 and 4, are determined so as not tooverlap with one another by considering the indices marking thepositions of the continual pilots as shown in Table 6 and the positionsof the scattered pilots, i.e., arrangement patterns.

FIG. 8 is a detailed block diagram of a transmitter according to anexemplary embodiment.

Referring to FIG. 8, the transmitter 300 may include a frame generator310, a pilot and reserved tone inserter 320, an inverse FFT (IFFT)calculator 340, a parallel/series converter 350, a PAPR reductionperformer 360, and a transmitting unit 330.

If the pilot and reserved tone inserter 320 is more specificallyexplained, signals at N-L points and signals regarding an L number ofreserved tones may be input to the pilot and reserved tone inserter 320.Here, zero (0) is inserted in the L number of reserved tones, instead ofdata.

The IFFT calculator 340 may perform an inverse Fourier transform togenerate a frame starting symbol, a data symbol and a frame closingsymbol in which pilots and reserved tones are inserted. Specifically,when a sum of parallel signals at N-L points and an L number of reservedtones are input to the IFFT calculator 340, an IFFT may be performed.

The parallel/series converter 350 may convert parallel signals outputfrom the IFFT calculator 340 into series signals and output the seriessignals. Specifically, the parallel/series converter 350 may outputsignals in the time domain by converting parallel signals into seriessignals.

The PAPR reduction performer 360 may reduce ratios of PAPR based onpilots and reserved tones.

Specifically, the PAPR reduction performer 360 may calculate reducingamounts of PAPR based on pilots and reserved tones, add the calculatedreducing amounts of PAPR with the series signals, and output the addedresults.

The PAPR reduction performer 360 may include a gradient algorithm (notillustrated), add the generated signals by the gradient algorithm (notillustrated) with the outputting signals from the IFFT calculator 340,and output the adding results. Here, the gradient algorithm (notillustrated) may reduce the ratios of PAPR of the output signals fromthe IFFT calculator 340 by using impulse signals corresponding toreserved tones.

Meanwhile, although not illustrated in FIG. 8, the transmitter 300 mayfurther include a memory (not illustrated) and a controller (notillustrated).

The memory (not illustrated) may store information about a number ofreserved tones and positions of the reserved tones according to the FFTsizes of OFDM. The gradient algorithm (not illustrated) generatessignals having impulse shapes by using the previously stored informationin the memory, and the generated impulse signals are stored in thememory (not illustrated).

Further, the memory (not illustrated) may transmit the information aboutthe number of reserved tones and positions of reserved tones to thecontroller (not illustrated). The controller (not illustrated) maytransmit this information to the pilot and reserved tone inserter 320 soas to allocate reserved tones without collision with data and pilotsaccording to the FFT sizes of OFDM and pilot positions.

Thereby, the pilot and reserved tone inserter 320 may allocate andinsert sub-carriers so as not to generate collision between pilots andreserved tones.

Further, the controller (not illustrated) may calculate a shift intervalof the scattered pilots according to OFDM symbol indices, and adjust aposition shift of reserved tones and phases of impulse signals. Becausesizes of impulse signals do not change even if positions of reservedtones circularly shift, a uniform PAPR reducing performance may bemaintained. Further, the shift interval may be internally calculated inthe pilot and reserved tone inserter 320, not in the controller (notillustrated), and transmitted to the controller (not illustrated) so asto calculate phases.

FIG. 9 is a detailed block diagram of the PAPR reduction performer 360according to an exemplary embodiment.

Referring to FIG. 9, the PAPR reduction performer 360 may include aP-wave generator 361, a peak extractor 362, a position circular shifter363, a phase rotator 364, a scaler 365, a complex adder 366, a PAPRcalculator 367, and a controller 368.

The P-wave generator 361 may generate P waves having impulse featureswith an L number of reserved tones while excluding input signals at anN-L point which are parallel signals among an N number of signals.Herein, the P waves are generated by repeatedly performingrandom-selecting at least one of an L number of reserved tones amongwhole signals, and selecting the smallest electrical power value amongP1-PN-1 values in which peak values of P0 are excluded.

Meanwhile, the peak extractor 362 may extract the maximum peak values ofinput signals at the N-L point.

Further, the position circular shifter 363 circularly shift positions ofthe P waves toward positions of the extracted maximum peak values.

The phase rotator 364 matches the circularly shifted P waves with phasesof the extracted peak values from the complex plane.

Further, the scaler 365 may scale values of the P waves so that peakvalues of the output signals obtained from calculating the input signalsat the N-L point with IFFT calculation can be less than a preset PAPRvalue.

In order to reduce the output signals obtained from calculating theinput signals at the N-L point with IFFT calculation and maximum peakvalues of the P waves to be less than a preset level, the complex adder366 may add the calculated values with the output signals obtained fromcalculating the input signals at the N-L point with IFFT calculation,and transmit to the PAPR calculator 367 as input values thereat.

The controller 368 may perform a feedback operation so that the inputPAPR calculated values can be less than the preset PAPR value. The aboveprocess is repeatedly performed until the input PAPR values are lessthan the preset PAPR value.

FIG. 10 is a block diagram of a receiver according to an exemplaryembodiment.

Referring to FIG. 10, the receiver 1300 may include a receiving unit1310 and a signal processor 1320.

The receiving unit 1310 may receive a frame including a frame startingsymbol, a data symbol and a frame closing symbol in which pilots andreserved tones are inserted, as described above.

The signal processor 1320 may estimate channels based on the pilots,perform signal-processing of the frame starting symbol, the data symboland the frame closing symbol by considering positions of the reservedtones, and extract data. Here, the reserved tones are inserted so as notto overlap the positions of pilots.

FIG. 11 is a detailed block diagram of the signal processor 1320 in thereceiver 1300, according to an exemplary embodiment.

Referring to FIG. 11, the signal processor 1320 may include aparallel/series converter 1321, an FFT calculator 1322, a data symbolextractor 1323, a data demodulator 1324, a memory 1325 and a controller1326.

The parallel/series converter 1321 may convert received signals in thetime domain into parallel signals, and output to the FFT calculator1332.

The FFT calculator 1332 may perform a fast Fourier transform of theinput signals, convert them into signals in the frequency domain, andtransmit the converted signals to the data symbol extractor 1323.

Here, the memory 1325 may output predetermined positions of the reservedtones inserted in the frame starting symbol, the data symbol and theframe closing symbol, according to an exemplary embodiment, and theoutput positions of the reserved tones are inputted to the controller1326.

The controller 1326 adjusts the positions of the reserved tones insertedaccording to the pilot positions of the received OFDM symbols in thereceiver 1310 so as not to collide with the pilot positions, and outputsto the data symbol extractor 1323.

The data symbol extractor 1323 may extract and output signals at thepositions except the positions of the reserved tones input from thecontroller 1326 among the input signals in the frequency domain from theFFT calculator 1322, i.e., signals corresponding to the data symbol.Accordingly, the data symbol extracted by the data symbol extractor 1323is input to the data demodulator 1324, and data demodulating calculationis performed.

Meanwhile, the reserved tones inserted in the frame starting symbol andthe frame closing symbol may be inserted at the positions shown in Table1.

Further, the reserved tones inserted in the data symbol may be insertedat the positions shown in Table 4.

Further, the pilots may be inserted at the positions shown in Table 6.

FIG. 12 is a flowchart illustrating a controlling method of atransmitter, according to an exemplary embodiment.

According to the controlling method of the transmitter illustrated inFIG. 12, a frame including a frame starting symbol, a data symbol, and aframe closing symbol as described above may be generated (S1510).

Next, pilots may be inserted in the frame starting symbol, the datasymbol and the frame closing symbol, and reserved tones may be insertedtherein so as not to overlap positions of the pilots (S1520).

Here, the pilots may be inserted in the data symbol according to apredetermined first arrangement pattern. And, the reserved tones may beinserted so as not to overlap the positions of the pilots. Pilots mayalso be inserted in the frame starting symbol and the frame closingsymbol according to a predetermined second arrangement pattern, andreserved tones may be inserted so as not to overlap the positions of thepilots. The predetermined second arrangement pattern may be determinedbased on the predetermined first arrangement pattern.

Further, in the data symbol, a first reserved tone may be inserted basedon the arrangement pattern of the pilots inserted therein, and a secondreserved tone may be inserted at a position shifted by a preset valuefrom the position of the first reserved tone.

Next, a frame in which the pilots and the reserved tones are insertedmay be transmitted (S1530).

Here, the reserved tones inserted in the frame starting symbol and theframe closing symbol may be inserted at the positions shown in Table 1.

Further, the reserved tones inserted in the data symbol may be insertedat the positions shown in Table 4.

The pilots may be inserted at the positions shown in Table 6.

Meanwhile, the controlling method of the transmitter illustrated in FIG.12 may further include performing IFFT calculation of the frame startingsymbol, the data symbol and the frame closing symbol in which pilots andreserved tones are inserted and outputting the calculating results,converting the parallel signals outputted by performing IFFT calculationinto series signals and outputting the series signals, and reducing aPAPR based on the pilots and the reserved tones.

Here, in reducing the PAPR, reducing amounts of the PAPR may becalculated based on the pilots and the reserved tones, the calculatedreducing amounts of the PAPR may be added to the series signals, and theadding results may be output.

FIG. 13 is a flowchart provided to explain the controlling method of areceiver according to an exemplary embodiment.

The controlling method of the receiver illustrated in FIG. 13 mayinclude an operation of receiving a frame including a frame startingsymbol, a data symbol and a frame closing symbol, as described above, inwhich pilots and reserved tones are inserted (S1610).

The controlling method may also include estimating channels based on thepilots, and extracting data by signal processing the frame startingsymbol, the data symbol and the frame closing symbol by consideringpositions of the reserved tones.

Here, the reserved tones are inserted so as not to overlap the positionsof the pilots.

Further, the reserved tones inserted in the frame starting symbol andthe frame closing symbol may be inserted at the positions shown in Table1.

Further, the reserved tones inserted in the data symbol may be insertedat the positions shown in Table 4.

Further, the pilots may be inserted at the positions shown in Table 6.

Meanwhile, a plurality of frames received by the receiver 1300 may betransmitted to a DVB-T2 transmitting system, and signaling areas of theframes may be areas where L1 signaling is transmitted.

According to the above exemplary embodiments, information included inthe signaling areas increase by reconstituting the information, andthus, data can be variously processed.

Meanwhile, according to an exemplary embodiment, a non-transitorycomputer readable recording medium storing programs which consecutivelyimplement the above controlling methods is provided.

For example, there is provided a non-transitory computer readablerecording medium storing programs which perform generating a frameincluding the frame starting symbol, the data symbol and the frameclosing symbol, inserting pilots in the frame starting symbol, the datasymbol and the frame closing symbol, inserting reserved tones so as notto overlap the positions of the pilots, and transmitting the frame inwhich the pilots and the reserved tones are inserted.

Further, for example, there is provided a non-transitory computerreadable recording medium storing programs which perform receiving aframe including the frame starting symbol, the data symbol and the frameclosing symbol in which pilots and reserved tones are inserted,estimating channels based on the pilots, and extracting data by signalprocessing the frame starting symbol, the data symbol and the frameclosing symbol based on the positions of the reserved tones.

The non-transitory computer readable recording medium indicates a mediumwhich store data semi-permanently and can be read by devices, not amedium storing data temporarily such as register, cache, or memory.Specifically, the above programs may be stored and provided innon-transitory computer readable recording medium such as compact disk(CD), digital versatile disk (DVD), hard disk, Blu-ray disk, universalserial bus (USB), memory card, or read-only memory (ROM).

Components, elements or units represented by a block as illustrated inFIGS. 3 and 8-11 may be embodied as the various numbers of hardware,software and/or firmware structures that execute respective functionsdescribed above, according to exemplary embodiments. For example, thesecomponents, elements or units may use a direct circuit structure, suchas a memory, processing, logic, a look-up table, etc. that may executethe respective functions through controls of one or more microprocessorsor other control apparatuses. These components, elements or units may bespecifically embodied by a module, a program, or a part of code, whichcontains one or more executable instructions for performing specifiedlogic functions. Also, at least one of the above components, elements orunits may further include a processor such as a central processing unit(CPU) that performs the respective functions, a microprocessor, or thelike.

Further, although the above block diagrams describing the transmitterand the receiver do not illustrate a bus, communication between theunits in the transmitter and the receiver may be performed through thebus. Further, each device may include a processor implementing the abovevarious processes such as CPU and microprocessor.

Further, the foregoing exemplary embodiments and advantages are merelyexemplary and are not to be construed as limiting the inventive concept.The present disclosure can be readily applied to other types ofapparatuses. Also, the descriptions of the exemplary embodiments of thepresent inventive concept are intended to be illustrative, and not tolimit the scope of the claims. For example, even if, according to theabove embodiments, the reserved tones are inserted such that theirpositions do not overlap positions of the pilots in all of the framestarting symbol, the data symbol and the frame closing symbol, thisnon-overlapping arrangement may be applied only to one or two of thesesymbols subject to a system condition.

What is claimed is:
 1. A receiving method comprising: receiving a frame from a transmitting apparatus; and processing the frame based on positions of tones for a peak to average power ratio (PAPR) reduction, wherein the frame comprises a preamble, at least one boundary symbol and data symbols; wherein the preamble comprises L1 signaling for the at least one boundary symbol and the data symbols, wherein the at least one boundary symbol comprises at least one of a symbol preceding a first data symbol of the data symbols or a symbol following a last data symbol of the data symbols, wherein the at least one boundary symbol comprises pilots inserted based on a first pattern and the data symbols comprise pilots inserted based on a second pattern, wherein the first pattern and the second pattern are different from each other, and wherein the pilots are not inserted at the positions of the tones in the at least one boundary symbol and the data symbols.
 2. The receiving method of claim 1, wherein the transmitting apparatus is configured to insert the pilots in the data symbols based on the second pattern, insert the tones in the data symbols such that the positions of the tones do not overlap positions of the pilots in the data symbols, insert the pilots in the at least one boundary symbol based on the first pattern, and insert the tones in the at least one boundary symbol such that the positions of the tones do not overlap the positions of the pilots in the at least one boundary symbol.
 3. The receiving method of claim 1, wherein the first pattern is determined based on the second pattern. 